I can usually create textures for OBJ files, either by applying a single-colored file or by first using UV Maker, but occasionally I come across downloads that refuse to accept textures, i.e. no pattern shows up on my monitor either before or after rendering. Strangely, some objects do accept a plain-colored, square JPG file, but not a patterned one. How can this be, and how can I effectively texture such illusive objects? 

The most common problem is that Poser 6 has trouble with

the normals of many objects.  Try checking the 'Normals Forward'

box in the materials room. 

Second, if the OBJ hasn't been UVmapped, P6 won't apply a

pattern, or will jumble the pattern.  Run it through UVmapper

and resave; doesn't matter which kind of map you choose.

Sorry, I should have explained that I'm using Poser 4. (I have but dislike Poser 6.) I did run the objects through UV Mapper but the "saved" texture map was blank.

Did you both save out the 'texture template' and resave the OBJ file with UV Mapper?  When you remap or add UVs, these changes must be save to the OBJ file - that is where the UV mapping is stored.

Robert

Thanks. No I didn't save the OBJ file -- I've never had to do that in the past... However I've now tried it, but to no effect. After mapping I saved the texture file (which was blank) and then saved the OBJ file, then imported the OBJ file back into Poser 4 and attempted wthout success to apply textures.

yes, in poser 4 it was easy to apply a single colour to an unmapped object. check the uvmapper forum for more details on which mapping to apply to a specific object.

You could try to use the grouping tool on that obj and just invert it....

Grouping tool? Sorry, I've never used it.

Quote - Thanks. No I didn't save the OBJ file -- I've never had to do that in the past... However I've now tried it, but to no effect. After mapping I saved the texture file (which was blank) and then saved the OBJ file, then imported the OBJ file back into Poser 4 and attempted wthout success to apply textures.

By blank texture file I assume you mean the template.  If you applied mapping, it cannot be blank.

Load the OBJ in UVMapper.  Can't remember what the free version looks like now, but should be a menu for mapping.  Choose Planar and accept the defaults.  Now do you see the mesh?  Save the template, and the OBJ  to a new name.

Some models have rudimentary UVs applied by the modeling app, so that they give no error when you import to UVMapper, but the UVs may not even be perpendicular to the surfaces, or will have the meshes piled on top of each other.  These cannot really be considered to be UV mapped.

Also, if it's an OBJ from the geometries folder, with P4 you need to delete the old RSR if you alter the OBJ and save it to the same name.  P4 will read the old RSR instead of the new OBJ.  If you delete it, Poser will build one for the remapped model.

John

Well, thanks, but I recognize nothing. In UVMapper I "load model," save the Texture map, and that's it. Choose Panar? No idea...

That does it! Perfect.
Many, many thanks for your patience and excellent  direction. (How do people learn these things?)

How do people learn these things ?

In many cases just the way you did.  :)    

The only stupid question is the one you didnt ask .

If you are planning a pattered texture experiment a bit with the box , and capped cylinder mapping .

You need to save the object file after selecting a new mapping type to save the mapping info correctly.

This thread caught my eye because I've been having trouble on getting an object to texture. And I had mapped it in UV Mapper. But after reading this I know what the prob was. I didn't know I needed to save the obj as well as the map. Now that I did that, I have a beautiful texture on my object. Soooo, a great big ol' THANK YOU, for this tip. :)

I sure wish there was some way that I could get notifications when UV Mapping issues are posted in the Poser forum.   Anyways I am sure glad to see markschum, lesbentley, BeyondVR, kuroyume0161, and ockham supplying the UV Mapping knowledge needed to get the job done.
Way to go guys!